Do I have to setup everything again after update?
Starting at 2.52 blender started saving it's startup.blend file in a new folder for every version. When you first run a new version of blender it sees that there is no startup.blend for it and looks for the previous version then gives you an option to copy the previous settings. I think this may only look for one or two previous versions, so if you update from 2.63 to 2.70 you may not get this option.

This manual page describes the locations that the startup.blend can be found. You can easily find the current startup.blend (and userpref.blend) and delete it so that you will get the option to copy previous settings. You could also locate an older startup.blend file and copy that to the new version folder.

On linux, the folder is located at ~/.config/blender/

On OSX, the folder is located at /Users/{user}/Library/Application Support/Blender/

On Windows, the folder is located at C:\Documents and Settings\{username}\AppData\Roaming\Blender Foundation\Blender\